WithBindMount methods failing when running in integration tests because paths aren't resolved relative to AppHost project

[DamianEdwards]

AppHost projects using the WithBindMount method to mount a host directory in a container can fail when running in the context of an integration test because the source path passed to WithBindMount isn't being resolved relative to the AppHost project.

Workaround is to explicitly resolve bind mount paths to full paths in the AppHost, e.g.:

var builder = DistributedApplication.CreateBuilder(args);

var grafana = builder.AddContainer("grafana", "grafana/grafana")
                     .WithBindMount(GetFullPath("../grafana/config"), "/etc/grafana", isReadOnly: true)
                     .WithBindMount(GetFullPath("../grafana/dashboards"), "/var/lib/grafana/dashboards", isReadOnly: true)
                     .WithEndpoint(targetPort: 3000, name: "grafana-http", scheme: "http");

builder.AddProject<Projects.MetricsApp>("app")
       .WithEnvironment("GRAFANA_URL", grafana.GetEndpoint("grafana-http"));

builder.AddContainer("prometheus", "prom/prometheus")
       .WithBindMount(GetFullPath("../prometheus"), "/etc/prometheus", isReadOnly: true)
       .WithEndpoint(/* This port is fixed as it's referenced from the Grafana config */ port: 9090, targetPort: 9090);

using var app = builder.Build();

await app.RunAsync();

static string GetFullPath(string relativePath) =>
    Path.GetFullPath(Path.Combine(Projects.MetricsApp_AppHost.ProjectPath, relativePath));

@davidfowl mentioned he had a fix for this at one point but that it didn't quite get in. We should fix this for preview.6